Locking mechanisms for egg cartons

ABSTRACT

Locking mechanisms for egg cartons having an integrally hinged tray and cover. The locking mechanism includes a locking flange that extends inwardly from the bottom of the cover&#39;&#39;s front wall and engages the underside of a protruding lip on the carton&#39;&#39;s tray when the carton is closed, and a depending flange that extends downwardly and outwardly from the inner edge of the locking flange to flex the locking flange over the protruding lip and into locking position as the tray and cover are moved into closed position.

United States Patent [72] Inventor George R. Scheul'ing 3,258,186 6/1966Greatman 229/2.5 Pittsburgh, Pa. 3,258,187 6/1966 Greatman 229/2.5 [21]App]. No. 813,616 3,298,594 1/1967 Makowski et al..... 229/45 [22] FiledApr. 4,1969 3,396,895 8/1968 Pearl et al 229/2.5 [45] g f 1x971 CPrimary Examiner-Davis T. Moot-head [73] ss'gnee a uppers ompanyAttorney-Finnegan, Henderson and Farabow Pittsburgh, Pa.

[54] LOCKING MECHANISMS FOR EGG CARTONS 9 Claims, 7 Drawing Figs. [52][1.5. CI 229/45, ABSTRACT: Locking mechanisms for egg canons having an229/2-5 integrally hinged tray and cover. The locking mechanism in- [51]Int. Cl B65d45/00 cludes a locking flange that extends inwardly from thebottom Fleld 44, of the covers front wall and engages the underside of a29 (M), 45 protruding lip on the cartonstray when the carton is closed,

and a depending flange that extends downwardly and out- [56] Referencescued wardly from the inner edge of the locking flange to flex the UNITEDSTATES PATENTS locking flange over the protruding llip and into lockingposi- 3,398,875 8/1968 Snow et al. 229/2.5 tion as the tray and coverare moved into closed position.

PATENTEDMAR slsm 3,668,916

sum 1 UF 2 INVEN'IOR GEORGE R. SCHEURING A'I'TURNI'IYS Emegan, fivzdmson(gzjajza ow SHEET 2 OF 2 PATENTED m 9 I97! mvmvmn GEORGE R. SCHEURINGiii/Ryan, j'fendzsolz' Qjagow v A'I'TUHNEYS LOCKMG MECHANISMS FOR EGGCARTONS This invention relates to packaging cartons, and moreparticularly to new and improved locking mechanisms for molded eggcartons.

Molded cartons with various types of integrally molded lockingmechanisms have been provided in the past for the packaging of eggs.Exemplary of one widely used type of locking mechanism provides a pairof lugs on the outer surface of a locking flap hingedly connected to thebottom tray of the carton that are matable with and extend throughcorresponding apertures in the front wall of the cartons lid to lock thelid to the tray.

Cartons utilizing this. type of locking mechanism, however, havegenerally proven unsatisfactory to housewives and other users, becausethey are difficult to open and close. The luglocking principle requiresflexing of the cartons walls by the user during opening and closing tofree the lugs from the apertures. Due to the inherent stiffness of thematerial used in the manufacture of such cartons, however, and theoutward pressure of the packaged articles, it is difficult for the userto flex the structure sufficiently to allow clearance for easy openingand closing. Such difficulties, of course, are not only inconvenient tothe user but render the carton and the packaged articles prone to bedamaged during repeated opening and closing of the carton.

In accordance with the present invention, new and improved lockingmechanisms are provided for a packaging carton in which the cartoncomprises a bottom section having a front wall and a rear wall; a coversection having a front wall and a rear wall; and a hinged connectionbetween the cover and bottom sections rear walls so that the cover canassume a closed-superimposed position with respect to the bottomsectron.

Interlocking means are provided on the front walls of the cover andbottom sections for releasably holding the carton closed. Theinterlocking means includes a longitudinal locking lip integral with andextending along at least a portion of the length of the top of thebottom sections front wall; a locking flange integral with andextending'inwardly from and along a portion of the length of the bottomof the cover sections front wall adjacent the locking lip, the lockingflange engaging the underside of the locking lip when the carton isclosed to hold the sections together; and a depending flange integralwith and extending downwardly and outwardly from the inner edge of thelocking lip as the sections are moved into a closed position to flex thelocking flange over the lip and into locking position.

Preferably, the packaging carton is an egg carton, and the carton andinterlocking means are of unitary molded construction.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory but arenot restrictive of the invention.

The accompanying drawings which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

Of the drawings:

FIG. 1 is a fragmentary perspective view of the front of an egg cartonin a partially open position and showing the locking mechanism of oneembodiment of this invention;

FIG. 2 is a broken view in vertical section of the egg carton of FIG. Iin an open position;

FIG. 3 is similar to FIG. 2 and shows a modification of the front wallof the cartons lid;

, FIG. 4 is a fragmentary and enlarged view in vertical section of thefront of the carton in FIG. l in a closed position;

FIG. 5 is a fragmentary perspective view of the front of an egg cartonin a partially open position and showing another embodiment of thelocking mechanism of this invention;

FIG. 6 is a broken view in vertical section of the egg carton of FIG. 5in an open position; and

FIG. 7 is a fragmentary and enlarged view in vertical section of thefront of the carton of FIG. 5 in a closed position.

Reference will now be made in detail to present preferred embodiments ofthe invention, examples of which are illustrated in the accompanyingdrawings.

The packaging cartons illustrated in the drawings and contemplated foruse withlocking mechanisms of this invention are egg cartons having acover section or lid 10 and a bottom section or tray 12. The cover andbottom sections rear walls 14 and 16, respectively, are hingedlyconnected by an integral web 18. Bottom section 12 has a plurality ofegg-accomodating cells arranged in parallel rows. While the number androws of cells may vary, the bottom section preferably consists of adozen cells arranged in two parallel rows of six cells each.

A wide variety of materials may be used in the manufacture of the cartonstructures illustrated in the drawings. Molded paper pulp, pasteboard,plastic and the like, for example, may be used. A preferred material,however, is thermoplastic foam, such as, for example, foam polystyrene,or other polymers, such as polyethylene, polypropylene,polyvinylchloride, and the like.' For purposes of illustration and aspreferred embodiments, the drawings show egg cartons and lockingmechanisms for the cartonsof unitary construction produced by vacuummolding or match-molding techniques from a sheet of polystyrene foam.

In accordance with the invention, interlocking means are provided on thefront walls of the cover and bottom sections for releasably holding thecarton closed. The relationship between the interlocking rneans and thetop and bottom sections of the carton, .as shown in the drawings, willbe used in the specification and claims for, clarity, but it is to beunderstood that the interlocking means may be reversed with I respect tothe cartons sections without departing from the scope of this invention.

As embodied, the interlocking means includes a longitudinal locking lip22 integral with and extending along at least a portion of the length ofthe top of bottom sections front wall 24, and a substantially horizontallocking flange 26 integral with and extending inwardly from and along aportion of the length of the bottom of the cover sections front wall 28adjacent locking lip 22. The upper surface 30 of locking flange 26engages the underside 32 of locking lip 22 when the carton is closed tolock the bottom and cover sections together.

A depending flange 34 integral with locking flange 26 extends downwardlyand outwardly fromJthe inner edge 36 of the locking flange to assist inthe locking and unlocking of the locking mechanisms.

During closing of the cartons, the inner surface 38 of depending flange34 engages the locking lip 22 and flexes locking flange 26 outwardlyover the outer edge 40 of lip 22 until the flange is free to snap backinto engagement with the underside of locking lip 22.

To open the container, the fingers are inserted between the bottomsection's front wall 24 and depending flange 34, and the flange ispulled upwardly and outwardly to pull locking flange 26 out ofengagement and over the outer edge 40 of locking lip 22.

As best shown in FIG. 1, there is provided an outwardly and laterallyextending flange 42 that extends around the bottom of the cover sectionsrear wall, its sidewalls, and a portion of its front wall, and acorresponding flange 44 on the top of the bottom sections walls, theflanges 42 and 44 being in substantial flush load-bearing engagementwhen the carton is closed.

In accordance with one embodiment of this invention, and as shown inFIGS. 1--4, locking lip 22 and locking flange 26 of the interlockingmeans extend substantially along the entire front walls of the bottomand top sections. As best shown in FIG, 1, a portion of the bottomsections flange 44 is raised along the bottom sections front wall 24intermediate its ends, and forms locking lip 22 of the interlockingmeans. Further, a portion of the cover sections flange 42 extendsdownwardly and outwardly along the sections front wall 28 and forms theleading edge 46 of the depending flange 34 of the interlocking means.

Thus, the upper surface 30 of locking flange 26 in this embodiment isabove the plane of engagement between thecover and bottom sectionsflanges 42 and 44, respectively, and approximately coplanar with lockinglip 22 so that the flange snaps into engagement with the underside 32 ofthe lip during closing for more positive locking.

Preferably, and as best shown in FIG. 2, locking flange 26 and dependingflange 34 are integrally molded with the cover sections front wall 28from a single sheet of thermoplastic foam. A bulge 48 is thus providedin front wall 28 to permit flexing of locking flange 26, primarilyaround the juncture 50 between bulge 48 and front wall 28, over lip 22during closing. Bulge 48 may be either rounded, as shown in FIG. 2, orof rectangular configuration, as shown in FIG. 3.

To effect a locking closure of the carton of FIGS. 1-4, cover section 10is rotated about hinge 18 toward closing relationship with bottomsection 12 and pressed downward until flanges 42 and 44 are in abuttingengagement. As the carton is closing, locking flange 26 is flexedoutwardly about juncture 50 by the inner surface 38 of depending flange34 riding over the outer edge 40 of locking lip 22. When the carton iscompletely closed as shown in FIG. 4, locking flange 26 snaps back intoengagement with the underside 32 of lip 22 to hold the sectionstogether.

When it is desired to open the carton, flange 34 is grasped and pulledupwardly and outwardly. This results in locking flange 26 flexing aboutjuncture 50 and being pulled out of engagement with looking lip 22.

In accordance with an alternative embodiment of this invention, and asshown in FIGS. 7, there is provided a plurality of intermittently spacedlocking lips 22 and corresponding locking flanges 26' on the front wallsof the carton similar to the single locking mechanism of the previousembodiment. As best shown in FIG. 5, the bottom sections flange 44 israised and recessed at spaced intervals along the sections front wallintermediate its ends, and forms the plurality of locking lips 22' ofthe interlocking means. Similarly, the cover section's flange 42includes a plurality of downwardly extending portions at spacedintervals along the sections front wall 28, and forms the leading edges46' of the plurality of depending flanges 34' of the interlocking means.Between the plurality of spaced locking flanges and lips, the flanges 42and 44 lie in abutting engagement with one another when the sections arein a closed-superimposed position.

Thus, the upper surface 30 of locking flanges 26 in this embodiment areabove the plane of engagement between the cover and bottom sectionsflanges 42 and 44, respectively, and are approximately coplanar withlocking lips 22 so that they snap into engagement with the undersides32' of lips 22' during closing for more positive locking.

Preferably, and as best shown in FIG. 6, locking flanges 26 anddepending flanges 34 are integrally molded with the cover sections frontwall 28 from a single sheet of thermoplastic foam. Hence, as in theprevious embodiment, a bulge 48 is provided in front wall 28 to permitflexing of the locking flanges over the locking lips.

In this embodiment, and as best shown in FIG. 7, locking lips 22' arerecessed so that the leading edges 46 of flanges 34 are substantiallycoplanar vertically with the leading edges of flanges 42 and 44. Hence,the locking mechanism of this embodiment does not project any singularelement beyond the normal boundaries of the carton substantiallypreventing the carton from being accidentally opened during handling.

Locking of the carton is effected in a manner similar to the previousembodiment, cover section being pressed down against bottom section 12to cause locking flanges 26' to snap under and into engagement withtheir corresponding lips 22'.

a To open the carton, the fingers are wedged between a number of flanges34 and the bottom sections front wall 24, and the flanges are pulledupwardly and outwardly, pulling flanges 26' out of engagement with thelocking lips.

To strengthen the interlocking means of this embodiment, locking flanges26' and locking lips 22 are located adjacent the carton ribs 51 thatform the egg-accommodating cells in the carton.

It can be seen therefore that the bottom and cover sections of bothembodiments can be easily, automatically, and positively locked togethersimply by moving the sections into closed position, and easily openedsimply by pulling upwardly and outwardly on the interlocking meansdepending flange 34.

The integral web 18 connecting the rear walls 14 and 16 of the cover andbottom sections, respectively, of both embodiments is preferablydoublycreased at 52 and 54 to provide a double hinge with a compressiblemidportion 56 between the creases that resiliently urges the cover andbottom sections apart so that locking flange 26 snaps tightly intoengagement with the underside of the bottom sections protruding lip 22when the carton is closed.

It is to be understood that the cartons described in the drawings andutilizing the locking mechanisms of this invention are preferred cartondesigns for eggs. The invention, however, is applicable to a variety ofegg carton shapes and other similar cartons. An egg carton, for example,having three parallel rows of four egg-accommodating cells each couldeasily be used with the present locking mechanism.

The invention thus provides new and improved locking mechanisms forpackaging cartons and particularly molded egg cartons. The lockingmechanism facilitates the easy closing, positive locking, and easyopening of the cartons without the need for applying excessive pressureand without fear of damage to the cartons or their contents. Further,the locking mechanisms of this invention can be'integrally molded withthe egg carton from a single sheet of suitable material usingconventional molding techniques.

The invention in its broader aspects is not limited to the specificdetails shown and described and departures may be made from such detailswithout departing from the principles of the invention and withoutsacrificing its chief advantages.

Iclaim:

l. A packaging carton comprising a bottom section having a front walland a rear wall; a cover section having a front wall and a rear wall;laterally extending flanges on the upper and lower edges of the walls ofthe bottom and cover sections, respectively, said flanges being insubstantial abutting engagement with one another when the sections arein closed position; interlocking means on the front walls of the coverand bottom sections for releasably holding the carton closed, saidinterlocking means comprising:

a. a protruding longitudinal locking lip integral with and extendingalong at least a portion of the length of the top of the bottom sectionsfront wall;

b. a locking flange integral with and extending inwardly from and alonga portion of the length of the bottom of the cover sections front walladjacent the locking lip, the locking flange engaging the underside ofthe locking lip when the carton is closed to hold the sections together;

c. a depending flange integral with and extending downwardly andoutwardly from the inner edge of the locking flange, whereby thedepending flange engages the locking lip as the sections are moved intoa closed position to flex the locking flange over the lip and intolocking position; and

(I. wherein said packaging carton further comprises a resilient hingedconnection between the cover and bottom sections rear walls for urgingthe sections apart so that the locking flange snaps tightly intoengagement with the underside of the locking lip when the sections aremoved into closed position.

2. The carton of claim 1, in the form of an egg carton, with the bottomsection having a plurality of egg-accommodating cells.

3. The carton of claim 1, wherein the carton is of unitary moldedconstruction.

4. The carton of claim 3, wherein the carton is formed of foamedpolystyrene.

5. The carton of claim 1, wherein a portion of said bottom sectionsfront wall flange is raised to form the longitudinal locking lip, and aportion of said cover sections front wall topsections intermediate 7.The carton of claim 1, including a plurality of spaced interlockingmeans along the front walls of the bottom and cover sections.

8. The carton of claim 7, wherein portions of the bottom sections frontwall flange are raised and recessed forming a plurality of locking lips,and corresponding portions of the cover section's front wall flangeextend downwardly to form the leading edges of the depending flanges.

9. The carton of claim 8, wherein the leading edges of the dependingflanges and the laterally-extending flanges are substantially coplanarvertically.

1. A packaging carton comprising a bottom section having a front walland a rear wall; a cover section having a front wall and a rear wall;laterally extending flanges on the upper and lower edges of the walls ofthe bottom and cover sections, respectively, said flanges being insubstantial abutting engagement with one another when the sections arein closed position; interlocking means on the front walls of the coverand bottom sections for releasably holding the carton closed, saidinterlocking means comprising: a. a protruding longitudinal locking lipintegral with and extending along at least a portion of the length ofthe top of the bottom section''s front wall; b. a locking flangeintegral with and extending inwardly from and along a portion of thelength of the bottom of the cover section''s front wall adjacent thelocking lip, the locking flange engaging the underside of the lockinglip when the carton is closed to hold the sections together; c. adepending flange integral with and extending downwardly and outwardlyfrom the inner edge of the locking flange, whereby the depending flangeengages the locking lip as the sections are moved into a closed positionto flex the locking flange over the lip and into locking position; andd. wherein said packaging carton further comprises a resilient hingedconnection between the cover and bottom section''s rear walls for urgingthe sections apart so that the locking flange snaps tightly intoengagement with the underside of the locking lip when the sections aremoved into closed position.
 2. The carton of claim 1, in the form of anegg carton, with the bottom section having a plurality ofegg-accommodating cells.
 3. The carton of claim 1, wherein the carton isof unitary molded construction.
 4. The carton of claim 3, wherein thecarton is formed of foamed polystyrene.
 5. The carton of claim 1,wherein a portion of said bottom section''s front wall flange is raisedto form the longitudinal locking lip, and a portion of said coversection''s front wall flange extends downwardly and outwardly to formthe leading edge of the depending flange.
 6. The carton of claim 5,wherein the locking lip and locking flange of the interlocking meansextend substantially along the entire front walls of the bottom and topsections intermediate their ends.
 7. The carton of claim 1, including aplurality of spaced interlocking means along the front walls of thebottom and cover sections.
 8. The carton of claim 7, wherein portions ofthe bottom section''s front wall flange are raised and recessed forminga plurality of locking lips, and corresponding portions of the coversection''s front wall flange extend downwardly to form the leading edgesof the depending flanges.
 9. The carton of claim 8, wherein the leadingedges of the depending flanges and the laterally-extending flanges aresubstantially coplanar vertically.